UK light-heavyweight Buatsi made a winning yet underwhelming debut to life under recent management with a points victory over Zach Parker in Manchester.
The Olympic medal winner's punch output seemingly secured him a judges' verdict in a close 10-round bout at the boxing arena.
But Parker landed significant shots, landing some telling clean blows in a fight where the styles didn't complement each other, with excessive holding marring the fight.
The officials scored it 96-94 to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my best display but what defines champions? They succeed," Buatsi commented in the ring as he was met by boos from the audience.
The Londoner returned to winning ways after his first professional defeat - an epic battle with Callum Smith in February - to earn a 20th pro success.
Several boxing experts thought Parker, 31, deserved the victory but the contender suffered the second loss of his 28-match professional journey.
The Champion Earns Triumph in Uneventful Affair
His career development has slowed in the past few years through contract problems and considerable time of inactivity.
Earlier forecast as the future of UK boxing, he now stands trying to fulfil that early promise - perhaps in what feels like a last chance - under fresh management.
He started carefully, with both competitors ready to take risks in a calculated opening few rounds.
Parker, whose only previous defeat came at super middleweight against his former opponent in two years ago after suffering a hand injury mid-fight, was participating in his second fight at light-heavyweight.
By the halfway stage, Parker had made it competitive, causing problems for Buatsi, who utilized a protective stance to narrowly win the more effective periods.
The audience's tolerance decreased amid frequent holding, with the challenger slipping to the canvas multiple occasions during close exchanges.
The underdog ended stronger, but several stanzas were hard to judge. However, former world champion the boxing analyst - working with the broadcast network - had it particularly wide for the challenger, scoring for Buatsi just a single round.
The victor advances, but with the presence of power puncher Benavidez, and Russian star Dmitry Bivol dominating the weight class, the road to world glory - judging by this showing - still looks steep.
Ricky Hatton Tribute Motivates Local Rivalry Fight
In the supporting bout, Arthur overcame Bradley Rea by divided decision in a terrific local rivalry fight to secure the continental title.
The stadium grew hushed for a extremely emotional homage ahead of the contest as a bell ceremony sounded in honor of local hero Ricky Hatton, who passed away aged 46 in September.
It was the initial significant broadcast fight night in the urban center since Hatton's death. As the concluding sound ended, the silence gave way to a shout of "only one Ricky Hatton".
The action during the bout matched the feeling. Arthur was floored by a significant blow flush on the chin in the initial stage, getting up unsteadily to his footing on the referee's count.
But the red-colored equipment of Arthur soon pressed ahead again. Across the ring, the opponent - in rival City blue - was damaged soon, noticeable damage appearing under his eye as the pair landed hard punches.
Rea, 27, landed power punches but the champion, 34, matched the intensity with stinging uppercuts as the pace hardly diminished over the full distance.
The victor narrowly won the result with official scores of even score, close margin and 115-112, but both fighters were persistent and courageous, all the qualities their hero the legend stood for.
